Method of producing alcohols



Dec. 5, 1939. L. M. cHRlsTENsEN METHOD 0F PRODUCING ALCOHOLS Filed July 9, 1957 Patented Dec.5, 1939 l i I v s UNITED' STATES PATENT 'OFFICE s 2,182,550 METHOD oF PRoDUcmG AtconoLs Leo M. Christensen, Atchison, Kans., assigner 'to The Chemical Foundation, Incorporated, New York, N. Y., a corporation of Delaware Application July 9, 1937, Serial No. 152,671

4 claims. (o1. 19t-13) This invention relates to the fermentation of which such residues are subjected to a special carbohydrates, more particularly to the producfermentation, particularly correlated with the tion of alcohols by fermentation. main fermentation step (i. e., the ethyl alcohol As is known,'in the typical method of. producfermentation) whereby such residues are con- 5 ing alcohol from grains, three essential steps are verted into valuable alcoholic and ketonic prod- 5 effected. In the first step the starchy material ucts, severally` or conjointly useful in the arts. is subjected to a suitable treatment to produce The principle of the invention is more specifia gelatinized and liquefied product. In the seccally illustrated as embodied in a special type of 0nd step the material is sacchariiied; that isto doublefermentation for the purpose of -producing say the starchis converted-to fermentable sugar. 'ethyl alcohol and other fermentation products l0` This conversion, in the typical case, is enzymatic designed for use as power alcohol. In the special and is e'ected by the use of malt, the conversion, process herein illustrated, therefore, the carboof course, being actually effected by the enzyme hydrate starting material isl substantially quantiof the malt, namely malt diastase. In the third tatively converted and the conversion products' yessential step the sugar solution, wort, is treated are fully utilized. i

with yeast to convert the sugar to alcohol. A major object of the present invention, there- AS kIlOWIl. the temperature, time, hydl'Ogen ion fore, is to convert the residues of alcohol fermen- OOIlCentra'On. WOIil-yeat rai'fO. and other imtation processes into valuable products. DOItant faCliOrS must be Carefully Controlled t0 Another object is to convert distillery slop into 2o, secure optimum yields. The resulting product,r valuable by-products.

i. e., a beer, is essentially an aqueous alcohol A further object is to devise an improved fersolution containing varying percentages of aloomentation process for converting carbohydrates 1101, Usually between 5% and- 3% AS' a result' of fermentation residues into more valuable prodof the fermentation, minor amounts of secondary uci-,5,

products are formed, such as fusel oils, esters, With these a lower fatty acids,and the like. The major byproducts of such a fermentation process are generally considered to be f usel oils, carbon dioxide', and spent grains, the latter containing the resid- 3ol ual proteins of the starting material.

In the past the spent grains were usually dried nd other equally important objects in view, the invention comprehends the concept of subjecting saccharied starches to fermentation, in any approved manner, to produce ethyl alcoholtherefrom andto subject the distillery... slop to aspecial treatment wherein the residual carbohydrates contained in the slop are 'conlilsuslggs ograe market elther as cattle food or verted to more valuable organic compounds. -The refinements of the invention include the concept ofgoglvrritligpurgglcttshis orlrilingvlgstlig iila of fractionang the conYersion Rmducts from the f l which is expectable from the quantity of starch two trfeatments eltfher slmmtaneously or sequen' originally entering the process. In other words, guy m the one msi-'mation apparatus thus sim' in the older methods the conversion of grains phfymgthe plant mstaua'tion and insuring to alcoholic products and carbon dioxide-was not marked Operating economles'h ti di 40.- complete. In the typical prior artmethod the In order to clearly explain t m'e oualt ai" 40 beer-still slop contained appreciable-amounts of grammatic i'llllSl'llain 0f a typica p an s unconverted carbohydrates which were disposed Shown' in the Single gure of the accompanying lof in a low-price market. The unconverted cardrawing' bohydrate content of the slop usually consists T0 Simphfy the drawmg and description it Wm largely of dexmns and in typical cases might nm be assumed that the starting material for the 45 as high as 15%, or more, of the original charge. ethyl 81001101 fermentatiOn Step iS a ypil WOrt Such residue is, in a sense, a partially converted Produ-Ced b Y any Suitable methd from any avail' product and presents a potential value far greater able material- It iS t0 be underSl'f00d 0f Course.

than the actual value received for it in the past. that in. the CQmPlete D IOCfSS vwidlrlg t0 the The present invention, in a broader aspect, present invention, the initial starting material 50 relates to a novel process of recovering the full is, in fact, any amy-laoeous SubstanceA (ie.,

value from such residues.l s grains, tubers and the like) and that this is The concept of utilizing the full potential valuetreated in theusual or any approved manner to of the carbohydrate residues of distillery slop is insure liquefaction and sacchariflcation. The l illustrated herein as embodied in a process in saccharication maybe effected by any desired ,y

method as, for example, by utilizing malt diastase or taka diastase.

Similarly, it will be assumed that the primary charge to the second or butyl alcohol fermentation stage comprises an unsaccharied mash produced by methods known to those skilled in the art.

The process will be described particularly with reference to the production of power alcohol; that is to say, the production of a product which, in addition to ethyl alcohol, may contain predetermined percentages of by-products of the process which present a high thermal value, such as the higher alcohols and/or predetermined percentages of other by-products, such as acetone, which function beneficially in the ultimate fuel. It is to be appreciated, as will be explained more fully, that by proper control of the operating conditions, aqueous or anhydrous alcohol, free from secondary products, may be produced.

In operating the process, a charge of saccharied mash produced, as noted, in any suitable manner, is charged from a mash tun (not shown) through the line I to the ethyl alcohol fermenter 2. In the fermenter the wort is pitched with any suitable yeast, preferably with Saccharomyces cerevisiae, in the proper inoculation ratio. In fermenter 2 the temperature and hydrogen ion concentration are carefully controlled, in the manner known to those skilled in the art, to secure eiiicient fermentation. It will be understood that the carbon dioxide generated during the fermentation is withdrawn and recovered in A any suitable form, such as carbon dioxide snow.

At the termination of the ethyl alcohol fermentation, the weak aqueous alcohol product is passed from the fermenter 2 through line 3, controlled by valve 3', to the beer well 4. In the beer well 4 the products produced in fermenter I are mixed or commingled with the products of conversion from the butyl alcohol fermenter unit, more particularly to be described. The aqueous solution is withdrawn from the beer well 4, at the times and in the amounts desired, and is passed through valve 5 in line 5 to the heat exchanger 6. In this exchangerthe beer is preheated by indirect contact with the hot distillery slop. The preheated beer then passes through line 1 and is discharged at an intermediate point in the beer Astm s.

The beer still may be of the usual design and construction, comprising a relatively elongated column in which preliminary concentration is effected by distilling off the alcohol. For this purpose a suitable heating means, such as the closed steam coil 9, is provided in the bottom of the still. The hot aqueous residue or slop containing the unfermented carbohydrates is passed, by way of line III and valve I0',-,to the heat exchanger 6 where it functions to preheat the beer passing to the distillation system and is itself commensurately cooled.

The slop, cooled to some degree in the passage through the heat exchanger, is then passed through line II to the cooler I2. In this cooler a suitable cooling medium is utilized and the temperature and speed of flow are so controlled as to reduce the temperature of the slop to approximately the optimum temperature for fermentation; that is to say, to approximately 37 or 38 C. The cooler I2 is preferably thermostatically controlled.

When the butyl beer is being distilled, or at any other time, it is not required` or desirable to return the slop to the butyl fermenters. The beer still slops are drawn oif through line IIa and taken to the feed recovery unit where the nonfermentable constituents are recovered as byproduct protein feed.

From the cooler I2 the slop or carbohydratecontaining liquor is passed through the line I 3 tothe butyl fermenter I4. In this fermenter the cooled slop may be treated alone or may be combined with unsaccharied mash fed thereto through the line I5.

In the fermenter I4 the charge is inoculated with a suitable culture, for example, Clostridium acetobatylz'cum. In ordinary operations an inoculation ratio of fromv one to twenty to one to fifty may be used, employing a 24-hour old transfer. In these circumstances, and operating at a temperature of approximately 38 C., fermentation is normallycomplete in about 30 hours.

The products of fermentation are withdrawn from fermenter I4 and passed through valve I6 and line I6 to be combined, in the beer well, with the products drawn off from the ethyl alcohol fermenter 2.

with this type f operation, therefore, it win be appreciated that the residue produced in the beer still; that is to say the beer slop, is treated so as to convert the fermentable components of the slop into valuable products. When utilizing Cl. acetobutylz'cum, as will be appreciated, the

carbohydrate material is converted into butanol, acetone and ethanol. In ordinary circumstances the material discharged from the butyl fermenter I4 to the beer well contains approximately six parts of normal butanol, three parts of acetone, and approximately one part of ethyl alcohol. Since the main fermentation is carried out in the ethyl alcohol fermenter 2, the alcoholic component of the beer which is subjected to distillation is, of course, largely ethyl alcohol. In normal operations the mixture of butanol, ethanol, and acetone recovered from the butyl fermenter I4 comprises approximately 2% to 3% ofthe beer in the beer well. i

It is to be appreciated that the broad concept of the present invention is the economical utilization of residues heretofore not chemically utilized. While the described method involves the fermentation of such residues, largely to acetone and N-butyl alcohol by'Cl. acetobutylcum,

it is to be appreciated that other microorganisms, capable of converting the carbohydrates into more valuable products, maybe employed. AFor example, if a larger conversion of the initial starting material into ethyl alcohol is desired, the residue or slop may beA inoculated with Bacillus acetoethylicum. In these circumstances the hydrogen ion concentration may be adjusted and the temperature controlled to produce a maximum yield of ethyl alcohol and a lower yield of the higher alcohols and acetone.

Similarly, by the proper choice of microorganisms, valuable products4 other than the lower aliphatic alcohols and acetones may be recovered from the beer still residues, as for example, butyric acid, acetic acid, propionic acid, lactic acid, andthe like.

It will be seen that the type ofprocess herein,

described is eminently flexible.. The respective quantitiesof the products to be treated in fermenters I and I4 may be varied over Wide ranges. Similarly the sequence of the twoA fermentations may be changed. Depending upon market demands, the process may be operated to produce relatively high or relatively low yields o1 butanol It i and acetone, such yields being modified within wide limits by the simple expedient of regulating the amount of the fresh charge fed to fermenter I4 through the line I5.

T'he-economy of the process, as before indicated, is accentuated by simultaneously distilling the fermentation products withdrawn from the two fermenters, and by utilizing available heat in the distillation residues for preheating the charge to fermenter I4. 'I'he process thus combines optimum thermal and chemical economies with maximum simplification of equipment.

As has been explained, the respective quantities of fermentation products produced in fermenters I and I4 may be greatly varied. In a typical operation for the production of power galcohol, for example, the process may be conducted to produce, in a given cycle, approximately 100 parts by volume of ethyl alcohol beer, in fermenter 2, and from 5 to 25 or more parts by volume of butyl alcohol beer in fermenter I4.

The mixed solution stored in beer well 4, as explained, is preheated by indirect heat exchange with the hot slop and is discharged into the beer still 8. The beer collecting in the kettle of the still is heated by the steam coil 9 and vapors passed overhead, preferably at a temperature in excess of 95 C., through the line II, to an intermediate point of the concentrating column I8.

' The hot aqueous residue or slop is passed sequentially through the preheater 6 and cooler I2 to the butyl fermenter I4, wherein the carbo-` l For this purpose the concentration column is provided with the heating coil I9. The mixed charge entering through line I1 is heated to vaporize the alcoholic and ketonic constituents.

The reflux condensate formed on the plates or decks of the column flow downwardly and countercurrently to the stream of evolved vapors, the latter being simultaneously scrubbed by the descending condensate.

At an intermediate point in the column a condensate comprised essentially of amyl and butyl alcohols is withdrawn through the line 2I and passed to 'a storage vessel. The vaporous mixture reaching the top of the column I8 is comprised of concentrated alcohol in admixture with the acetone content of the charge. Water condensate collected in the base of the column is withdrawn in the usual manner through line 20.

In the preferred practice of the invention the vapors ypassing overhead from the column I8 are further fractionated to separate the ethyl alcohol fromthe acetone. After such separation the concentrated aqueous .alcohol is passed to a dehydration stage, such as an anhydrous column, to removevthe residual water and produce anhydrous alcohol. As will be understood, when the ethyl alcohol produced inthe process is to beemploye'd as a fuel it is not essential that the quantitative separation of acetone from the alcohol be effected. On the contrary a small percentage of acetone in the ultimate fuel is sometimes desirable, as for example in those caseswhere the alcohol is to be blended with gasoline. It is desirable, however, to remove a considerable percentage of theacetone since its presence in large amounts interferes with the dehydration of the ethyl alcohol. Hence the present process may be operated to remove all of the acetone, or to reduce it toa predetermined low percentage, as for example to 1% or less in the alcohol passing to the anhydrous column or other dehydrating it.

The removal of the acetone contained in the alcohol is effectively secured by fractional condensation, although any other method may be used. As shown, the concentrated, aqueous althus utilized as a reflux wash for the ascendingI alcoholic vapors.

Vapors which are uncondensed in the dephlegmator 23 pass through the line 25 into the condenser 26. This condenser, like dephlegmator 23, is preferably positively cooled by circulating a suitable cooling medium therethrough.

The temperature conditions within the condenser 26 are accurately controlled so as to preferentially or fractionally condense the aqueous alcohol, while retaininglower boiling point constituents, such'as acetone, inthe vapor phase. This condenser stage is therefore controlled to reduce the temperature of the incoming vapors below approximately 78.5, i. e. the boiling point of ethyl alcohol, but above 57 C., i. e. the -boiling point of acetone. This temperature control may, if desired, be automatically maintained by meansof a suitable thermostatic element operative, for example, to regulate the ow of the cooling medium through the condenser.

The fraction condensed in condenser 26 comprises a 95% aqueous alcohol with, if desired, up to 1% of acetone. 'I'his condensate is passed through the line 21 to a suitable dehydrating unit, such as the anhydrous column 3I. In this column water may be removed from the alcohol by suitable methods of azeotropic distillation. Instead of passing the condensed aqueous alcohol to an anhydrous column, such alcohol may be treated to remove the water by suitable methods of chemical dehydration, such as is described in U. S. Patent 2,038,357.

e The vapors uncondensed in condenser 26 pass 0E through the -line 28 `to the final condenser 29.

These low boiling point vapors, consisting largel ly of acetone, are liqueed in the final condenser and are withdrawn through line 30 to storage. It will be appreciated that with this type of process substantially all of the amylaceous charge is converted into valuable compounds. The ethyl alcohol' contained in the beer produced in fermenter I4, as well, as that produced in fermenter 2, is simultaneously concentrated and dehydrated. tSimilarly the fusel oil content of the beer from fermenter 2 is co-distilled and co-condensed with the butyl alcohol produc in the fermenter I4. I

When the alcohol produced by the process is to be employed for power alcohol, in admixture Vwith gasoline, predetermined amounts of the secondary products produced may be utilized. For example, the acetone separated and recovered in the ultimate fuel. Again, if desired, the fusel oil fraction drawn ofi:` through line 2l maybe further Afractionated and certain of the fractions, such as the normal butyl alcohol, may also be added in predetermined percentages to the anhydrous alcohol produced, when such is to be employed as power alcohol.

When secondary products, such as butanol, acetone and the like, are not-directly utilized by admixture with gasoline, they may, of course, separately and profitably be disposed of in the chemical markets.

While a preferred modification of the inven# tion has been described, it is to be understood that this is given merely to illustrate the fundamental principle of the invention and as typifying other equivalent methods of insuring maximum recovery of valuable products by substantially complete utilization of the amylaceous starting material.

I claim:

1. A method of producing anhydrous alcohol and other valuable products from amylaceous starting materials which comprises fermenting a saccharied amylaceous mash in one fermenter to produce ethyl alcohol; distilling the products of fermentation in a distillation zone to recover a concentrated aqueous alcohol; passing the residue from the distillation zone to a second fermenter and fermenting the carbohydrate content of the residue to produce ethyl alcohol, butyl alcohol and acetone; passing the products of conversion from the second fermenter, together with the products of conversion from the first fermenter', to the said distillation zone for co-dismentation in a distillation zone to recover a concentrated' aqueous alcohol; passing the residue from the distillation zone to a second fermenter and mixing such residue in the fermenter with an amylaceous mash; fermenting the mixture in the second fermenter to produce ethyl alcohol,

butyl alcohol and acetone; passing the products of conversion of the second fermenter, together with the products of conversion from the first fermenter, to the said distillation zone for codistillation therein; and fractionating the distilled vapors to recover a concentrated aqueous alcohol substantially free from higher and lower boiling point constituents.

3. A method of producing alcohol and other valuable products from amylaceous starting material which comprises fermenting a saccharifled amylaceous mash in a fermenter. with Saccharomgl/ces cerevisiae to produce ethyl alcohol therefrom; distilling the products of fermentation in a distillation zone to recover a concentrated aqueous alcohol; passingvthe residue from the distillation zone to a second fermenter and adding to the residue in such fermenter an amylaceous mash; inoculating the material in the second fermenter with Clostridium acetobutylicum to produce ethyl alcohol, butyl alcohol and acetone; passing the products of conversion from the second fermenter, together with the products of conversion from the rst fermenter, to the said distillation zone for co-distillation therein; fractionating the distilled vapors to recover a concentrated aqueous ethyl alcohol substantially free from higher alcohols and acetone. y

4. A method of producing alcohol and other valuable products from amylaceous starting material which comprises fermenting a saccharied amylaceous mash in a fermenter with Saccharomyces cerevisiae to produce ethyl alcohol therefrom; distilling the products of fermentation in a distillation zone to recover a concentrated aqueous alcohol; passing the residue from the distillation zone to a second fermenter and adding to the residue in such fermenter an amylaceous mash; inoculating the material in the second fermenter with Clostridium acetobutylicum to proy duce ethyl alcohol, butyl alcohol and acetone; passing the products of conversion from the second fermenter, together with the products of conversionirom the iirst fermenter, to the said distillation zone for co-distillation therein; fractionating the distilled vapors to recover a concentrated aqueous ethyl alcohol substantially free from higher alcohols and acetonethen subjecting the concentrated aqueous ethyl alcohol to dehydration to produce anhydrous alcohol.

LEO M. CHRISTENSEN. 

